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Machinery In Rough, Light Knife Encountered Problems?

Jun 04, 2019

Machinery in rough, light knife encountered problems? Don't worry. Listen to the processing experience summarized by ALLES CNC engineers.


General Principles of Knife Path

1. open rough

Under the maximum load of the machine tool, in most cases, we should choose the largest knife, the largest amount of feed and the fastest possible feeding. In the case of the same knife, the feed is inversely proportional to the feed. Normally, the load of machine tools is not a problem. The principle of tool selection is mainly based on whether the two-dimensional angle and three-dimensional arc of the product are too small. After choosing a good tool, the length of the tool can be determined. The principle is that the length of the tool is larger than the processing depth. For large workpieces, the interference of the chuck should be considered.


2. light knife

The purpose of light knife is to meet the processing requirements of surface finish and appropriate allowance reserved. Likewise, the light knife should be chosen as large as possible and as fast as possible, because the fine knife needs a long time, and the most suitable feed and feed should be used. Under the same feed, the larger the transverse feed, the faster the cutter feed, the surface feed is related to the smoothness after processing, the size of feed is related to the surface shape of the surface, leaving the smallest margin, using the largest knife, the fastest speed and appropriate feed without harming the surface.


Clamping method

1. All clamps are vertical and horizontal.


2. Gear clamping: 

The clamping height should not be less than 10 mm. The clamping height and the processing height must be specified when processing the workpiece. The processing height should be about 5 mm higher than the plane of the vise in order to ensure its firmness without harming the vise. This kind of clamping belongs to general clamping. The clamping height is also related to the size of the workpiece. The larger the workpiece, the higher the clamping height.


3. Splint clamping: 

Splint code is used on the workbench, and workpiece is locked on the splint by screw. This clamping is suitable for workpieces with insufficient clamping height and larger processing force. Generally, medium and large workpieces have better effect.


4. Code iron clamping: 

when the workpiece is large and the clamping height is insufficient, and silk reeling is not allowed to be locked at the bottom, the code iron clamping is used. This kind of clamping needs to be twice clamped. Firstly, four corners are coded and other parts are processed, then four sides are coded and four corners are processed. When clamping twice, do not let the workpiece loose, first code and then loose. You can also code two sides first and process the other two sides.


5. Tool clamping:

 The diameter is more than 10 mm, the clamping length is not less than 30 mm; the diameter is less than 10 mm, the clamping length is not less than 20 mm. The clamping of cutters should be firm, and the cutters should be strictly protected from collision and directly inserted into the workpiece.


Classification of Cutting Tools and Their Applicable Scope

1. Classification by material

White steel knife: easy to wear and tear, used for roughening copper and small steel.

Tungsten steel knife: used for angle clearing (especially steel) and smooth knife.

Alloy knife: similar to tungsten steel knife.

Purple knife; used in high speed cutting, not easy to wear.


2. Divide by the knife head

Flat-bottomed knife: for flat and straight side, clearing plane angle.

Ball knife: It is used for light knife and light knife in all kinds of curved surface.

Bull nose knife (unilateral, bilateral and five sides): used for roughening of steel (R0.8, R0.3, R0.5, R0.4).

Coarse knife: used for roughening, pay attention to the remaining method (0.3).


3. According to the cutter rod

Straight rod cutter: Straight rod cutter is suitable for various occasions.

Inclined rod knife: but not suitable for straight face and face with slope less than rod slope.


4. According to the blade

Two-edged, three-edged and four-edged, the more the number of edges, the better the effect, but the more work done, the corresponding adjustment of speed and feed, the longer the life of the number of edges.


5. The difference between ball knife and flying knife

Ball knife: When concave ruler is smaller than ball ruler and flat ruler is smaller than ball R, light can not be obtained (bottom angle can not be cleared).

Flying knife: The advantage is that it can clear the bottom angle. Comparisons of the same parameters: V=R*_rotates a lot faster (flying knife), the things that shine out with great force are bright, flying knife is mostly used for contour shape, sometimes flying knife does not need mid-light. The disadvantage is that the concave size and plane ruler are less than the flying knife diameter in less time.


CNC with EDM, Copper Gong's Practice

1. Under what circumstances do you need to be a copper bull?

1) The knife can't go down at all to be a copper bull. There is still something that can't go down in a copper bull. The shape of the knife is protruding and needs to be divided again.

2) The knife can go down, but the easily broken knife also needs to be made copper gong, which depends on the actual situation.

3) The products with sparkle pattern are required to be coppers.

4) Copper can not be made, the bone position is too thin and too high, vulnerable and easily deformed, deformation and spark deformation in processing, at this time need inserts.

5) The surface of the East and West (especially the surface will be smooth and even) machined by copper Gong can overcome many problems in Gong and drawing.

6) When accurate shape or excess allowance is required, rough copper coppers must be made.


2. Copper Emperor's Practice

Select the face to be made of copper, fill the face to be made up, or extend the face to ensure that all the edges of copper are larger than the edges to be struck without harming the surface of other products, remove unnecessary and undesirable plane angles (the intersection of plane angles is deeper glue level), fill in regular shapes, find out the maximum shape of copper, use a boundary and then projection to the supporting surface; determine the size of the reference frame. Cut off the bracket, and then the copper map is basically completed. Material preparation: length * width * height, length and width (> Ymax and Xmax) as the reference frame, the actual length and width of copper material must be larger than the reference frame on the map. The theoretical dimension of height (> Copper Gong) +reference frame height + clamping height.

 

Drawing Fixed Number Problem

1. In the absence of an off-the-shelf processing surface, in the four-sided plane, the center is zero to the origin, the top is zero, and when the top surface is uneven (for Copper Gong), the remaining amount is 0.1, that is, when the number of collisions occurs, the actual value is 0 (z), which is lower than 0.1 on the graph.


2. When there are ready-made facets, make the ready-made facets on the drawing 0 (z) and the plane energy into the middle. Otherwise, the actual height, width, length and the difference between the ready-made facets and the drawings should be checked and programmed according to the actual material. Generally speaking, the size of the drawing is processed first and then the shape of the drawing is processed.


3. When multi-bit processing is required, the first bit (standard bit) should have a good Gong for the other bits, the length, width and height of gongs, and all the next processing benchmarks should be based on the surface that has been processed last time.


4. Location of inserts: put the inserts in the whole, put a certain height on the bottom, and then raise the height of the drawings. The plane is divided into the whole, and the height is locked by upsetting wires under the drawings. The height is squared and straight, and the roughness can be divided into the largest shapes. Cut a clamp, according to the relative position of the inserts and fixtures, and then place the original point of the drawings in the center of the fixture. Point.


Choice of Rough Cutting Path

1. Surface Digging

1) The key is the choice of scope and area.

The area of tool path processing is: the selected surface in the selected range is the termination surface, and the principle is that the tool can go down from the highest point to the lowest point. The best choice is the whole surface, the boundary can only be the area to be processed, no surface extends less than half of the tool diameter distance, because there is enough margin left on other surfaces so that automatic protection; the best extension of the lowest line, because there is no R gong at the lowest point.

2) Choice of knife: If the knife can't enter helically or obliquely or the area that can't be machined can't enter the area of the knife sealed, leaving for the second roughing.

3) Before a light knife, it is necessary to open all the uncut areas, especially small angles, including two-dimensional, three-dimensional and sealed areas, otherwise the knife will be broken. Secondary roughening: generally use three-dimensional groove selection range, flat-bottom knife, can use plane groove and external tool path. In the case of no damage to other surfaces, the cutter center to the selected boundary is generally not refined. The cutter is spiral feed with fast two-way angle depending on the situation. The angle is 1.5 degrees and the height is 1. When the shape of the groove is strip, if the cutter can not spiral down, it is inclined feed. Generally, the filter is opened, especially the surface of the cutter is rough, the feed plane is not low, so as to avoid collision with the cutter and the safety height is not low.

4) Return knife: Relative return knife is not usually used, absolute return knife is used, and relative return knife is used when there is no island.


2. Planar Digging

Milling all kinds of planes, concave and flat grooves, when milling part of the open plane, the boundary should be fixed. The principle can feed the cutter (larger than one cutter diameter), the open part is larger than half the cutter diameter, and the outer part should be closed.


3. shape

When the selected plane is suitable for the shape stratification, the shape stratified lifting knife (plane shape) is used. When the lifting point and the lower point are one point, the z plane general lifting knife is not needed, and the relative height is not used as far as possible; the direction of correction is generally right correcting (along the knife).


4. Tool Path Setting for Mechanical Correction

Correction number is 21. Correct the machine by computer. Feed the knife vertically. Where the knife can't pass, change the R to no margin.


5. Contour shape

Suitable for the closed surface, if the open surface is four circles, the cover cover, if the four circles or non-Four circles, the range and height (a certain arc feed roughness) should be selected for the roughening situation: the processing distance in any plane is less than one tool diameter, and if it is larger than one tool diameter, the larger tool or two contour shapes should be used.


6. Surface streamline

With the best uniformity and brittleness, it is suitable for light knife to replace contour shape in many cases.


7. Radiation knife path

Suitable for the case of large holes in the middle (less use). Notes: marble knife, knife is not sharp, knife is too long, when the workpiece is too deep, it can not go up and down; two knife paths should be divided on both sides of the sharp angle of the workpiece, it can not be crossed, and the edge of the light knife should be prolonged (with arc in and out of the knife).


Clear angle

1. The clearing angle here is the two-dimensional dead angle, which has not been reached in the previous process. If the light knife needs to go to the place, it should clear the angle first and then the light knife. If the angle is too small and deep, it can be divided into several knives, not too many places with a small knife.


2. Clean three-dimensional angle: open some small grooves, some three-dimensional corner.


3. Easy to break knives, we must take into account such as fine knives, too long, too large processing capacity (mainly Z direction, depth direction).


4. Knife path: only small angle (R0.8) and two-dimensional plane angle can be cleared with two-dimensional shape; parallel knife path can be used; contour shape can be used; there is a place where the knife can not go to the surface and the dead angle of the shape can not be reached, the knife should be sealed first, and finally the small gap in the large surface should be sealed first.


Medium light

1. Medium Light: Steel as a surface and Medium Light as a thin genius.


2. Principle: There is more margin between layers when the big knife is roughened, which is a working procedure for better effect when the light knife is opened.


3. Characteristic: Rapid cleaning, big knife flying knife can also be, large feed, large spacing; no need to worry about surface quality; flat workpiece does not need mid-light; contour workpiece does not need mid-light; contour workpiece does not need mid-light, when the contour shape is rough, two processes can be put together in a smaller way, referring to the distance between surface allowance and layer; no mid-light is needed, and an important factor is the material for work, the more material is needed. Hard, then consider medium light; medium light processing direction and light knife roughening is better than such processing things will be good, even.


Light knife

Light knife is to meet the assembly requirements of various products and models, so it is very prudent to give different tool path settings and parameter settings according to different requirements.


1. The cutting height and final height of the light knife are changed to 0. The tolerance design is within 1 wire, and no filtering is needed (the smaller the workpiece is, the smaller the tolerance is, the tolerance will affect the appearance).


2. The front die and parting surface should achieve the best smoothness, the rear die can be secondary, and other non-matching and vacancy avoidance can be rough points.


3. Knife path design is determined by the following factors:

1) Specific shape (such as plane and other surfaces), steep surface and flat surface.

2) Whether there is a sharp angle between the two sides (the sharp angle is separated).

3) Whether the requirements of the two parts are different (whether or not to leave a margin, the amount of the margin, and the requirement of smoothness are different).

4) The problem of protective surface in light knife is a big problem. The machined surface must be protected against errors in advance and according to the requirements of protective surface. Range protection, zero protection regardless of error, height range and plane range; protective surface protection.

5) The problem of tool path lengthening. In light knife, when the tool path is machined to the edge, it is better to make arc feed and withdraw knife, otherwise the face will be slightly lengthened beforehand.

6) Lifting knife in light knife. Lifting knives is a waste of time, so try to avoid lifting knives.

Method 1: Set up the knife clearance (small gap)

Method 2: Cover up the knife (small gap)

Method 3: Avoid gap (large gap)

Method 4: Extend to the same height when contouring

7) In the light knife feed problem, the first knife feed must be from the workpiece, avoid vibration and damage to the workpiece, all light knives must be set into the knife.

8) Tool wear problem: when the workpiece is large, more than one knife is needed to finish the same workpiece.



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